To reset your password, please run the script password-reset.php located in
/var/www/html/clustercontrol/app/tools/

$ cd /var/www/html/clustercontrol/app/tools/
$ php -e password-reset.php

OR

use the S9S tool to change password from Command Line 

$ s9s user --change-password --new-password=YOURNEWPASSWORD USERNAME
For more details, please refer to the Severalnines User Guide.